/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.volley.toolbox;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.Request.Method;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.ProtocolVersion;
import org.apache.http.StatusLine;
import org.apache.http.entity.BasicHttpEntity;
import org.apache.http.message.BasicHeader;
import org.apache.http.message.BasicHttpResponse;
import org.apache.http.message.BasicStatusLine;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLSocketFactory;

/**
 * An {@link HttpStack} based on {@link HttpURLConnection}.
 */
public class HurlStack implements HttpStack
{
	
	private static final String HEADER_CONTENT_TYPE = "Content-Type";
	
	/**
	 * An interface for transforming URLs before use.
	 */
	public interface UrlRewriter
	{
		/**
		 * Returns a URL to use instead of the provided one, or null to indicate
		 * this URL should not be used at all.
		 */
		public String rewriteUrl( String originalUrl );
	}
	
	private final UrlRewriter mUrlRewriter;
	private final SSLSocketFactory mSslSocketFactory;
	
	public HurlStack()
	{
		this( null );
	}
	
	/**
	 * @param urlRewriter Rewriter to use for request URLs
	 */
	public HurlStack( UrlRewriter urlRewriter )
	{
		this( urlRewriter, null );
	}
	
	/**
	 * @param urlRewriter Rewriter to use for request URLs
	 * @param sslSocketFactory SSL factory to use for HTTPS connections
	 */
	public HurlStack(
			UrlRewriter urlRewriter,
			SSLSocketFactory sslSocketFactory )
	{
		mUrlRewriter = urlRewriter;
		mSslSocketFactory = sslSocketFactory;
	}
	
	@Override
	public HttpResponse performRequest(
			Request< ? > request,
			Map< String, String > additionalHeaders ) throws IOException, AuthFailureError
	{
		String url = request.getUrl();
		HashMap< String, String > map = new HashMap< String, String >();
		map.putAll( request.getHeaders() );
		map.putAll( additionalHeaders );
		if( mUrlRewriter != null )
		{
			String rewritten = mUrlRewriter.rewriteUrl( url );
			if( rewritten == null )
			{
				throw new IOException( "URL blocked by rewriter: " + url );
			}
			url = rewritten;
		}
		URL parsedUrl = new URL( url );
		HttpURLConnection connection = openConnection( parsedUrl, request );
		for( String headerName : map.keySet() )
		{
			connection.addRequestProperty( headerName, map.get( headerName ) );
		}
		setConnectionParametersForRequest( connection, request );
		// Initialize HttpResponse with data from the HttpURLConnection.
		ProtocolVersion protocolVersion = new ProtocolVersion( "HTTP", 1, 1 );
		int responseCode = connection.getResponseCode();
		if( responseCode == -1 )
		{
			// -1 is returned by getResponseCode() if the response code could not be retrieved.
			// Signal to the caller that something was wrong with the connection.
			throw new IOException( "Could not retrieve response code from HttpUrlConnection." );
		}
		StatusLine responseStatus = new BasicStatusLine( protocolVersion, connection.getResponseCode(), connection.getResponseMessage() );
		BasicHttpResponse response = new BasicHttpResponse( responseStatus );
		if( hasResponseBody( request.getMethod(), responseStatus.getStatusCode() ) )
		{
			response.setEntity( entityFromConnection( connection ) );
		}
		for( Entry< String, List< String > > header : connection.getHeaderFields().entrySet() )
		{
			if( header.getKey() != null )
			{
				Header h = new BasicHeader( header.getKey(), header.getValue().get( 0 ) );
				response.addHeader( h );
			}
		}
		return response;
	}
	
	/**
	 * Checks if a response message contains a body.
	 * @param requestMethod request method
	 * @param responseCode response status code
	 * @return whether the response has a body
	 * @see <a href="https://tools.ietf.org/html/rfc7230#section-3.3">RFC 7230 section 3.3</a>
	 */
	private static boolean hasResponseBody(
			int requestMethod,
			int responseCode )
	{
		return requestMethod != Request.Method.HEAD && !( HttpStatus.SC_CONTINUE <= responseCode && responseCode < HttpStatus.SC_OK ) && responseCode != HttpStatus.SC_NO_CONTENT && responseCode != HttpStatus.SC_NOT_MODIFIED;
	}
	
	/**
	 * Initializes an {@link HttpEntity} from the given {@link HttpURLConnection}.
	 * @return an HttpEntity populated with data from <code>connection</code>.
	 */
	private static HttpEntity entityFromConnection( HttpURLConnection connection )
	{
		BasicHttpEntity entity = new BasicHttpEntity();
		InputStream inputStream;
		try
		{
			inputStream = connection.getInputStream();
		}
		catch( IOException ioe )
		{
			inputStream = connection.getErrorStream();
		}
		entity.setContent( inputStream );
		entity.setContentLength( connection.getContentLength() );
		entity.setContentEncoding( connection.getContentEncoding() );
		entity.setContentType( connection.getContentType() );
		return entity;
	}
	
	/**
	 * Create an {@link HttpURLConnection} for the specified {@code url}.
	 */
	protected HttpURLConnection createConnection( URL url ) throws IOException
	{
		return ( HttpURLConnection )url.openConnection();
	}
	
	/**
	 * Opens an {@link HttpURLConnection} with parameters.
	 * @return an open connection
	 */
	private HttpURLConnection openConnection(
			URL url,
			Request< ? > request ) throws IOException
	{
		HttpURLConnection connection = createConnection( url );
		
		int timeoutMs = request.getTimeoutMs();
		connection.setConnectTimeout( timeoutMs );
		connection.setReadTimeout( timeoutMs );
		connection.setUseCaches( false );
		connection.setDoInput( true );
		
		// use caller-provided custom SslSocketFactory, if any, for HTTPS
		if( "https".equals( url.getProtocol() ) && mSslSocketFactory != null )
		{
			( ( HttpsURLConnection )connection ).setSSLSocketFactory( mSslSocketFactory );
		}
		
		return connection;
	}
	
	@SuppressWarnings( "deprecation" )
	/* package */ static void setConnectionParametersForRequest(
			HttpURLConnection connection,
			Request< ? > request ) throws IOException, AuthFailureError
	{
		switch( request.getMethod() )
		{
			case Method.DEPRECATED_GET_OR_POST:
				// This is the deprecated way that needs to be handled for backwards compatibility.
				// If the request's post body is null, then the assumption is that the request is
				// GET.  Otherwise, it is assumed that the request is a POST.
				byte[] postBody = request.getPostBody();
				if( postBody != null )
				{
					// Prepare output. There is no need to set Content-Length explicitly,
					// since this is handled by HttpURLConnection using the size of the prepared
					// output stream.
					connection.setDoOutput( true );
					connection.setRequestMethod( "POST" );
					connection.addRequestProperty( HEADER_CONTENT_TYPE, request.getPostBodyContentType() );
					DataOutputStream out = new DataOutputStream( connection.getOutputStream() );
					out.write( postBody );
					out.close();
				}
				break;
			case Method.GET:
				// Not necessary to set the request method because connection defaults to GET but
				// being explicit here.
				connection.setRequestMethod( "GET" );
				break;
			case Method.DELETE:
				connection.setRequestMethod( "DELETE" );
				break;
			case Method.POST:
				connection.setRequestMethod( "POST" );
				addBodyIfExists( connection, request );
				break;
			case Method.PUT:
				connection.setRequestMethod( "PUT" );
				addBodyIfExists( connection, request );
				break;
			case Method.HEAD:
				connection.setRequestMethod( "HEAD" );
				break;
			case Method.OPTIONS:
				connection.setRequestMethod( "OPTIONS" );
				break;
			case Method.TRACE:
				connection.setRequestMethod( "TRACE" );
				break;
			case Method.PATCH:
				connection.setRequestMethod( "PATCH" );
				addBodyIfExists( connection, request );
				break;
			default:
				throw new IllegalStateException( "Unknown method type." );
		}
	}
	
	private static void addBodyIfExists(
			HttpURLConnection connection,
			Request< ? > request ) throws IOException, AuthFailureError
	{
		byte[] body = request.getBody();
		if( body != null )
		{
			connection.setDoOutput( true );
			connection.addRequestProperty( HEADER_CONTENT_TYPE, request.getBodyContentType() );
			DataOutputStream out = new DataOutputStream( connection.getOutputStream() );
			out.write( body );
			out.close();
		}
	}
}
